[PATCH] arm64: errata: add module build workaround for erratum #843419

[Catalin Marinas]

On Wed, Sep 16, 2015 at 12:16:37PM +0100, Will Deacon wrote:
> Cortex-A53 processors <= r0p4 are affected by erratum #843419 which can
> lead to a memory access using an incorrect address in certain sequences
> headed by an ADRP instruction.
> 
> There is a linker fix to generate veneers for ADRP instructions, but
> this doesn't work for kernel modules which are built as unlinked ELF
> objects.
> 
> This patch adds a new config option for the erratum which, when enabled,
> builds kernel modules with the mcmodel=large flag. This uses absolute
> addressing for all kernel symbols, thereby removing the use of ADRP as
> a PC-relative form of addressing. The ADRP relocs are removed from the
> module loader so that we fail to load any potentially affected modules.
> 
> Signed-off-by: Will Deacon <will.deacon at arm.com>

I don't particularly like but, well...

Acked-by: Catalin Marinas <catalin.marinas at arm.com>